It is known in accordance with the teaching in U.S. Pat. No. 1,988,634 to provide a key card having separate conclusions displayed thereon. A plurality of screen cards is adapted to be placed over the key card. Each screen card is provided for a distinguishing characteristic of one or more of the conclusions of the key card and having means thereon for indicating the characteristic. A plurality of openings in each card for exposing those conclusions to which the characteristic applies, and the openings are of different sizes to indicate the certainty, probability and possibility of the presence of the characteristic in the exposed conclusions.
Another known system is disclosed in U.S. Pat. No. 3,186,111 for indexing information which includes a deck that comprises a large number of property cards and a reference card. All of the cards are the same size and shape so that selected groups of cards may be stacked uniformly. All of the property cards are semitransparent so that a person can easily see through at least two cards in ambient light. Identical coordinate locations on the respective cards are superposable when selected cards are stacked with each of the coordinate locations corresponding to a different item. Each of the property cards is perforated at each coordinate position corresponding to each item with respect to which the property represented by that card is associated. Each of the property cards is perforated in a different pattern of coordinate positions than each of the other property cards, but some of the property cards are perforated in the same positions. Each property card bears a legend identifying the property associated with items represented by perforations in that card. Such a system is known as a "peek-a-boo" retrieval system.
A further retrieval system is covered in U.S. Pat. No. 3,215,848 which is directed to a permanent memory for storing items of information as visual indications. A record contains an item of information in the form of visual indicators. Means is provided for comparing the item on the record with the items stored in the memory, and means derives from each comparison an output signal but only when the extent of the match between the items compared exceeds a given value. Specifically, this patent postulates for each disease the existence of a spectrum of "significances" for each positive symptom (but not negative findings). Said "significance" is entered in a line (or other form) of varying total light transmittance corresponding to the "significance". An overlying patient film recording positive findings is then compared with the master film by aligning the symptom lines of the two films and passing light through the superimposed films. A measure "indicative of the probability that a patient has a particular disease" is said to be obtained by comparing the amount of light which passes through the "two films as compared with the amount of light which would pass through the spectrum of the disease alone."
U.S. Pat. No. 2,795,705 is directed to a system wherein the amount of light detected by a photocell at any given instant is compared with the amount of light that would be obtained if there were actually a mismatch. Thus, since the amount of light detected by the photocell due to mismatch at a single information area will be small compared with the amount of light due to a mismatch, the system can readily detect the difference between the two. This provides greater accuracy in identification of recorded information.
None of these systems is capable of utilizing the pertinent function of the probability of occurrence of findings in a class in comparison with the information regarding an object which is a possible member of the class in the manner of the present invention. It is of note, however, that other systems may be thought of as special cases in this system by the use of appropriate function modification cards, but the statistical models they represent have extremely limited applicability to the real world.